\Header{qqmath}{Q-Q Plot with Theoretical Distribution}
\keyword{dplot}{qqmath}
\begin{Description}\relax
Quantile-Quantile plot of a sample and a theoretical distribution\end{Description}
\begin{Usage}
\begin{verbatim}
qqmath(formula, distribution = qnorm, f.value = ppoints,...)
\end{verbatim}
\end{Usage}
\begin{Arguments}
\begin{ldescription}
\item[\code{formula}] formula of the form \code{\textasciitilde{} x | g1 * g2 * ...},
where \code{x} must be a numeric.

\item[\code{distribution}] a quantile function that takes a vector of
probabilities as argument and produces the corresponding
quantiles. Possible values are \code{qnorm,qunif} etc.
Distributions with other required arguments need to be passed in as
user defined functions. This is also passed in as an argument to the
panel function (though not used by the default panel function), 
and the prepanel function if specified, for use in the bery commonly
used \code{(pre)panel.qqmathline}.

\item[\code{f.value}] function of a single integer (representing sample
size), returning a vector of probabilities corresponding to which
quantiles should be plotted.

\item[\code{...}] Other arguments
\end{ldescription}
\end{Arguments}
\begin{Details}\relax
These and all other high level Trellis functions have several
arguments in common. These are extensively documented only in the
help page for \code{xyplot}, which should be consulted to learn more
detailed usage.\end{Details}
\begin{Value}
An object of class ``trellis''. The `update' method can be used to
update components of the object and the `print' method (usually called
by default) will plot it on an appropriate plotting device.\end{Value}
\begin{Author}\relax
Deepayan Sarkar \url{deepayan@stat.wisc.edu}\end{Author}
\begin{SeeAlso}\relax
\code{\Link{xyplot}}, \code{\Link{panel.qqmath}},
\code{\Link{panel.qqmathline}}, \code{\Link{prepanel.qqmathline}},
\code{\Link{Lattice}}\end{SeeAlso}
\begin{Examples}
\begin{ExampleCode}
qqmath(~ rnorm(100), distribution = function(p) qt(p, df = 10))
data(singer)
qqmath(~ height | voice.part, aspect = 1, data = singer)
\end{ExampleCode}
\end{Examples}

